Analysis of Observed Contamination Through SAGE III's First Year on Orbit

SAGE III is a payload on the International Space Station that conducts measurements of ozone and other atmospheric constituents through the use of a moderate resolution spectrometer with an operating wavelength range of 290 nm to 1550 nm. Because of the optically sensitive nature of the payload, a suite of eight Thermoelectric Quartz Crystal Microbalances (TQCMs) were included to monitor the operating environment. During the rst year of operation, the SAGE III TQCMs were instrumental in detecting several periods of higher contamination and localizing their sources. A clear window made from quartz crystal covers the instrument assembly's aperture. Under nominal operating conditions, this window is only open during science gathering activities. However, if the rates of contamination accumulation are detected to be above the background rate, the window will be kept closed during science gathering to protect the optically sensitive instrument mirror. An analysis of the signal transmissions through the window for the wavelengths of 290 nm to 1550 nm has been conducted to determine any possible degradation of the window and potential in uence on science data collected to date, and established a baseline for future analysis

Performance and Security of Group Signature in Wireless Networks

A Group signature protocol is a cryptographic scheme that decouples a user identity and location from verification procedure during authentication. In a group signature scheme, a user is allowed to generate signatures on behalf of other group members but identity and location information of the signer is not known by a verifier. This ensures privacy, authentication and unlinkability of users. Although group signature is expensive to implement, its existential anonymity, non-repudiation and untraceablility properties make it attractive especially for resources-constrained devices in wireless network. A general group signature scheme usually contains six basic phases: setup (or key generation), join, message signing (or signature generation), signature verification, open and user revocation. In this paper, an evaluation of the performance of group signature based on three of the phases mentioned above is considered and its security in wireless networks examined. The key generation, signing and verification algorithms are implemented in Java 8. A proof of security of group signature by implication is also presented

Criteria for deterministic single-photon emission in two-dimensional atomic crystals

The deterministic production of single-photons from two dimensional materials promises to usher in a new generation of photonic quantum devices. In this work, we outline criteria by which single-photon emission can be realised in two dimensional materials: spatial isolation, spectral filtering and low excitation of quantum emitters. We explore how these criteria can be fulfilled in atomically thin transition metal dichalcogenides, where excitonic physics dictates the observed photoemission. In particular, we model the effect of defects and localised strain, in accordance with the most common experimental realisations, on the photon statistics of emitted light. Moreover, we demonstrate that an optical cavity has a negative impact on the photon statistics, suppressing the single-photon character of the emission by diminishing the effect of spectral filtering on the emitted light. Our work provides a theoretical framework revealing criteria necessary to facilitate single-photon emission in two-dimensional materials and thus can guide future experimental studies in this field

Negative Differential Resistance in van der Waals Heterostructures Due to Moiré-Induced Spectral Reconstruction

Formation of moir\'{e} superlattices is common in Van der Waals heterostructures as a result of the mismatch between lattice constants and misalignment of crystallographic directions of the constituent two-dimensional crystals. We discuss theoretically electron transport in a Van der Waals tunnelling transistor in which one of the electrodes is made of two crystals forming a moir\'{e} superlattice at their interface. By investigating structures containing either the aligned graphene/hexagonal boron nitride heterostructure or twisted bilayer graphene, we show that negative differential resistance is possible in such transistors as a consequence of the superlattice-induced changes in the electronic density of states and without the need of momentum conserving tunnelling present in high-quality exfoliated devices

How to Stop the Bleed: First Care Provider model for developing public trauma response beyond basic hemorrhage control

INTRODUCTION: Since 2013, the First Care Provider (FCP) model has successfully educated the non-medical population on how to recognize life-threatening injuries and perform interventions recommended by the Committee for Tactical Emergency Casualty Care (C-TECC) and the Hartford Consensus in the disaster setting. Recent programs, such as the federal Stop The Bleed campaign, have placed the emphasis of public training on hemorrhage control. However, recent attacks demonstrate that access to wounded, recognition of injury, and rapid evacuation are equally as important as hemorrhage control in minimizing mortality. To date, no training programs have produced a validated study with regard to training a community population in these necessary principles of disaster response. METHODS: In our study, we created a reproducible community training model for implementation into prehospital systems. Two matched demographic groups were chosen and divided into trained and untrained groups. The trained group was taught the FCP curriculum, which the Department of Homeland Security recognizes as a Stop the Bleed program, while the untrained group received no instruction. Both groups then participated in a simulated mass casualty event, which required evaluation of multiple victims with varying degree of injury, particularly a patient with an arterial bleed and a patient with an airway obstruction. RESULTS: The objective measures in comparing the two groups were the time elapse until their first action was taken (T1A) and time to their solution of the simulation (TtS). We compared their times using one-sided t-test to demonstrate their responses were not due to chance alone. At the arterial bleed simulation, the T1A for the trained and untrained groups, respectively, were 34.75 seconds and 111 seconds (p-value = .1064), while the TtS were 3 minutes and 33 seconds in the trained group and eight minutes in the untrained groups (physiologic cutoff) (p-value = .0014). At the airway obstruction simulation, the T1A for the trained and untrained groups, respectively, were 20.5 seconds and 43 seconds (p-value = .1064), while the TtS were 32.6 seconds in the trained group and 7 minutes and 3 seconds in the untrained group (p-value = .0087). Simulation values for recently graduated nursing students and a local fire department engine company (emergency medical services [EMS]) were also given for reference. The trained group\u27s results mirrored times of EMS. CONCLUSION: This study demonstrates an effective training model to civilian trauma response, while adhering to established recommendations. We offer our model as a potential solution for accomplishing the Stop The Bleed mission while advancing the potential of public disaster response

Error Analysis of Stored Grain Inventory Determination

Citation: Turner A., J. Jackson, N. Koeninger, S. McNeill, M. Montross, M. E. Casada, J. M. Boac, R. Bhadra, R. G. Maghirang, and S. A. Thompson. 2016. Error Analysis of stored grain inventory determination. Transactions of ASABE 59(3): 1061-1072Estimation of the quantity of stored grain is important for crop insurance, financial statements, and inventory control. Traditionally, the height of grain has been measured using weighted tape measures, and the volume is subsequently computed using standard geometric shapes (cylinders and cones) along with visual correction of the grain surface. Field measurements by four trained USDA Farm Service Agency and crop insurance agents on older farm-sized bins (8.2 to 11.0Â m, or 27 to 36 ft, in diameter) resulted in standard deviations between 0.02 and 0.30 m for the equivalent height when the grain surface was not level. The largest errors were observed with off-center surface profiles. When the grain surface inside the bins was manually leveled, the standard deviation of the equivalent height varied between 0.02 and 0.18 m. Error propagation analysis was performed to evaluate the error in measuring the volume of stored grain caused by the uncertainty associated with measuring the bin diameter and grain height as a function of the ratio of equivalent level grain height to bin diameter (EH/D). The errors were examined using an assumed range of uncertainties to explore how each factor contributed to the error in different scenarios. The uncertainty increased as the EH/D ratio decreased, especially in small-diameter bins with shallow grain heights where the volume bounded by the surface profile of the grain represented a large percentage of the total volume within the structure. Therefore, any errors in defining the surface profile resulted in large errors in the total estimated volume of grain in small-diameter bins. Conversely, for large-diameter bins with large grain heights, the surface profile represented a very small percentage of the total volume of grain. Consequently, any errors in defining the profile produced much smaller errors in the total grain volume. For accurate measurements, defined as a standard deviation of 1.2 cm (0.04 ft) in the diameter and 7.6 cm (0.25 ft) in the equivalent level height, the overall uncertainty in the volume measurement never exceeded 5% for smaller bins (10 m in diameter). A sensitivity analysis was performed on the three most common methods used to convert the measured volume to a quantity of grain. In each method, the quantity of grain stored in a bin is the product of the volume measurement and the pack factor. With all three methods, the sensitivity of the pack factor determination resulted in an error of less than 1% in the estimated total quantity of stored grain. The volume measurement accounted for the majority of the error in the estimation of bin inventory. As a result, accurate measurement of the bin volume is critical for determining the quantity of stored grain

Why do models overestimate surface ozone in the Southeast United States

Ozone pollution in the Southeast US involves complex chemistry driven by emissions of anthropogenic nitrogen oxide radicals (NOx  ≡  NO + NO2) and biogenic isoprene. Model estimates of surface ozone concentrations tend to be biased high in the region and this is of concern for designing effective emission control strategies to meet air quality standards. We use detailed chemical observations from the SEAC4RS aircraft campaign in August and September 2013, interpreted with the GEOS-Chem chemical transport model at 0.25°  ×  0.3125° horizontal resolution, to better understand the factors controlling surface ozone in the Southeast US. We find that the National Emission Inventory (NEI) for NOx from the US Environmental Protection Agency (EPA) is too high. This finding is based on SEAC4RS observations of NOx and its oxidation products, surface network observations of nitrate wet deposition fluxes, and OMI satellite observations of tropospheric NO2 columns. Our results indicate that NEI NOx emissions from mobile and industrial sources must be reduced by 30–60 %, dependent on the assumption of the contribution by soil NOx emissions. Upper-tropospheric NO2 from lightning makes a large contribution to satellite observations of tropospheric NO2 that must be accounted for when using these data to estimate surface NOx emissions. We find that only half of isoprene oxidation proceeds by the high-NOx pathway to produce ozone; this fraction is only moderately sensitive to changes in NOx emissions because isoprene and NOx emissions are spatially segregated. GEOS-Chem with reduced NOx emissions provides an unbiased simulation of ozone observations from the aircraft and reproduces the observed ozone production efficiency in the boundary layer as derived from a regression of ozone and NOx oxidation products. However, the model is still biased high by 6 ± 14 ppb relative to observed surface ozone in the Southeast US. Ozonesondes launched during midday hours show a 7 ppb ozone decrease from 1.5 km to the surface that GEOS-Chem does not capture. This bias may reflect a combination of excessive vertical mixing and net ozone production in the model boundary layer

Prolonged viral replication and longitudinal viral dynamic differences among respiratory syncytial virus infected infants

© 2017 2017 International Pediatric Research Foundation, Inc. BackgroundLongitudinal respiratory syncytial virus (RSV) dynamics have not been well studied despite the existence of factors favoring prolonged RSV replication including high mutation rates allowing rapid evolution and potential escape from immune control. We therefore measured viral load in previously RSV-naive infants over prolonged time spans.MethodsDuring 2014-2015, quantitative nasal aspirates were collected from 51 RSV-PCR+ infants. Multiple parallel assessments of viral loads were quantified at each collected time point using a well-validated real-time quantitative reverse transcriptase polymerase chain reaction assay. After observing viral load rebound phenomenon in some infants, the viral dynamics of 27 infants with sufficient longitudinal viral load data points were analyzed using the pre-defined criteria for viral rebound. Additional analyses were performed comparing age with viral rebound, viral clearance rates, and viral load area-under-the-curve (AUC VL).ResultsThe 51 infants (303 nasal aspirate samples; mean of 5.9 per patient) exhibited slower than expected viral clearance. Lower age trended toward slower viral clearance and greater AUC VL. Six infants had detectable viral loads ≥1 month after symptom onset. Ten of twenty-seven evaluable subjects exhibited viral rebound and this rebound was age-dependent (P=0.0259). All but one rebounder were rebound; likely representing viral mutational immune escape